textproduct: Quad Cities

KEY MESSAGES

- Patchy to areas of fog possible early this morning, becoming dense in some locations, especially north and west of Cedar Rapids and Dubuque.

- Drier conditions today before an active pattern and humid conditions return this weekend through the middle of next week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 137 AM CDT Thu Aug 6 2026

Compared to Wednesday, today will be drier for much of the area outside some lingering showers (20-30% chance) along and south of a line between Memphis, MO and Princeton, IL this morning. The shortwave trough that brought us the on-and-off showers and storms yesterday is forecast to propagate eastward as a high pressure slides in to replace the surface boundary stalled over the CWA. Temperatures will be slightly below average for August with highs in the upper 70s to low 80s and lows tonight in the low to mid 60s with light and variable winds.

Friday throws a wrench into the dry conditions with the next shortwave trough diving in from the northwest on the backside of a longwave trough over central Canada. This is going to force another weak surface trough to move into the area and act as a focal point for some scattered showers and storms (30-50% coverage). A wind shift to out of the southwest will also enable low-level WAA to increase highs a few degrees, adding to the limited instability ahead of this boundary. Current REFS guidance has 1500-2250 J/kg of SBCAPE across eastern Iowa with the greatest 0-6 km bulk shear of 35-40 knots displaced to the west. With this disconnect between instability and shear, the severe threat with any developing storms should be limited. The SPC has a Marginal Risk (Level 1 out of 5) for severe weather for locations to the north and west of a line from Keosauqua, IA to Dubuque, IA where there should be brief overlap in bulk shear and SBCAPE prior to sunset. Primary hazard would be damaging winds with the potential for an MCS development.

By Friday night, both the surface and shortwave troughs will shift to our southeast as another weak high pressure settles over the area for Saturday. Lows again will be seasonable in the low to mid 60s. Dry and seasonable conditions persist into Saturday, but they will not last long heading into the second half of the weekend.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 137 AM CDT Thu Aug 6 2026

Saturday night-Monday...As the longwave trough that has been stationary over central Canada finally propagates eastward, zonal upper-level flow over the Northern Rockies and Plains returns, shifting the direction of the storm track along with it. A subtle shortwave is expected to deepen a low pressure along the leeward side of the Northern Rockies and Front Range Saturday into Saturday night. This low pressure system will help generate a warm front along the pressure gradient from the high pressure over the region that will be pulled northward into Iowa and western Illinois. The frontal passage and convergence along a developing LLJ is likely to generate scattered showers with embedded thunderstorms (50-70% coverage) Saturday night into Sunday and set the stage for a warming and moistening trend early next week. By Monday, the low pressure moves across northern Iowa and southern Minnesota into Wisconsin, keeping storm chances on the table and pushing a cold front southward. These storms do have a potential to turn severe, especially in northern Iowa, where WAA and low-level wind shear close to the low pressure center could enable some convective organization, but it is too early to determine the severity. What is more certain is the front stalling out across the CWA Monday night into Tuesday as dynamical support is lost.

Tuesday-Wednesday...Another weak shortwave moves across the Central Rockies, spawning a Front Range low on the tail-end of the stationary front draped across the Central Plains and Midwest. This could lead to a deformation zone to form near the surface across the CWA and allow for rounds of storms to develop but also pool moisture (and therefore, dew points). While it is difficult to address the excessive heat and/or severe potential this far out, there is growing confidence (50-70% chance per 05.12z LREF guidance) that dew points will once again be back in the low-to-mid 70s making conditions outdoors feel muggy for middle of next week.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 137 AM CDT Thu Aug 6 2026

A MVFR stratus deck is currently impacting MLI and BRL and is approaching CID and DBQ. Ceilings are expected to lower throughout the night with lower visibilities (1.5 to 3 miles) forming due to patchy fog and mist. There is a 60-80% chance for ceilings less than 1 kft, putting all sites in IFR conditions. While the probabilities for ceilings less than 0.5 kft are lower, current conditions and model trends near MLI and BRL hints towards a higher likelihood which prompt the prevailing groups being included. After 14 UTC, the stratus deck is forecast to lift and scatter out from northwest to southeast into the afternoon hours with VFR conditions returning areawide heading into this evening.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.